Vacuum extraction tube



. July 7 1959 R. E. CHARLTON, JR., ET AL VACUUM EXTRACTION TUBE 2 Sheets-Sheet 1 Filed June 4, 19,56

INVENTORS RICHARD E. CHAR LTON,JR,

VERNA L. PAYN E mfiagfmw ATTORNEYS United States Patent VACUUM EXTRACTION TUBE Richard E. Charlton, Jr., Fairfax, and Verna L. Payne,

Shawmut, Ala., assignors to West Point Manufacturing Company, West Point, Ga., a corporation of Georgia Application June 4, 1956, Serial No. 589,224

1 Claim. (Cl. 15-306) This application relates to apparatus for impregnating fabric, and in particular to an improved vacuum extraction tube for the extraction of excess impregnant from non-woven fabric.

Non-woven fabrics are commonly manufactured by suspending textile fibers in an air stream, and then passing the air stream through a foraminous member to deposit a web of fibers thereon in random fashion. Phillips et al. Patent 2,648,876, issued August 18, 1953, illustrates a preferred method of manufacture. Since the nonwoven web when initially deposited is light and fluify, and possesses little strength, it is customary to apply a liquid binder or bonding agent thereto. As disclosed in the Phillips et al. patent referred to, the fabric is passed immediately after formation to impregnating apparatus and then to drying or drying and curing apparatus, whereby the web is stabilized and given adequate strength and other properties for further handling or ultimate use.

Before leaving the impregnating apparatus, the wet and weak fabric, supported by a wire screen or similar foraminous element, is passed over a vacuum extraction tube adapted to suck air therethrough and remove excess impregnant therefrom. It is a principal object of the present invention to provide in impregnating apparatus for nonwoven fabric and efficient and durable vacuum extraction tube, adapted to remove excess impregnant from the fabric at high rate exceeding and easily controlled uniformity.

A further object of the invention is to provide a vacuum extraction tube for removing excess impregnant from screen supported non-woven fabric, which is adapted to make an effective and efficient seal with the supporting screen.

Another object of the invention is to provide a vacuum extraction tube adapted to remove excess impregnant from screen supported non-woven fabric without condensing the fabric or disturbing the fiber orientation thereof.

Still another object is to provide a vacuum extraction tube readily disassembled for cleaning. Further objects will be in part obvious and in part pointed out hereinafter.

The invention and the novel features thereof may best be made clear from the following description and the accompanying drawings, in which:

Figure 1 is a side elevational view of an impregnating apparatus for non-woven fabric incorporating a vacuum extraction tube according to the present invention;

Figure 2 is a plan view of the impregnating apparatus of Figure 1;

Figure 3 is a sectional view through the improved vacuum extraction tube, taken on the line 3-3 of Figure 2;

Figure 4 is a plan view of the vacuum extraction tube, on enlarged scale;

Figure 5 is a sectional view of the vacuum extraction tube taken on the line 5-5 of Figure 4, and

Figure 6 is a sectional view through the vacuum extraction tube taken on the line 6-6 of Figure 4.

Referring to the drawings in detail, the impregnating apparatus illustrated in Figures 1 and 2 includes a frame- 10 supporting a tank 12 adapted to contain impregnating liquid. An immersion drum 14 is rotatably mounted on the frame in such manner that the bottom portion thereof extends below the level 16 of the impregnating liquid in the tank, and a foraminous conveyor belt member, pref erably a continuous wire screen 18, is provided to sup port the fabric 20 in passage under the immersion drum. As shown, the screen 18 passes about rollers 22, 24, 26 and 28, the rollers 22 and 24 being disposed on opposite sides of the immersion drum, and approximately level with its axis, whereby the upper flight of the belt therebetween extends under and partially around the immersion drum as shown. The newly deposited fabric web 20 passes over the roller 22 onto the screen 18, and is carried by the screen under the immersion drum, and through the liquid in the tank, moving in the direction indicated by arrow 30. On emerging from the tank, the wet fabric passes over rollers 24 and 26, and then immediately to drying appartaus not shown.

Between the rollers 24 and 26, a vacuum extraction tube indicated generally as 32 is mounted on the frame and extends transversely of the screen, the upper surface of the extraction tube being disposed immediately below and in supporting contact with the screen 18. The tube 32 is preferably of square cross-sectional shape, and constructed of upper and lower U-shap ed members 34 and 36 assembled in facing relationship by means of bolts 38 joining their flanges 40 and 42, respectively. The flanges may extend the entire length of the members 34 and 36, but as shown are limited to the major central portions thereof. Outwardly of the flanges, any space between members 34 and 36 may be substantially closed by insert pieces 44, which may be welded to either of the members, as shown in Figure 6.

Regardless of the shape of the tube 32, the upper surface 46 thereof must be flat and of substantial width. The tube 32 is desirably constructed of corrosion and Wear resistant material, such as stainless steel, and the upper surface 46 thereof, which is subjected to severe usage, is provided preferably with a heavy and polished coating of chromium.- A continuous slot 48 extends longitudinally of the upper tube surface 46, communicating with the interiorof the tube. The length of the slot is substantially coextensive with, and preferably slightly greater than, the width of the fabric 20 to be treated. The dimensions of the slot 48 and the width of the upper tube surface 46 are of considerable importance. For optimum function in connection with a wire screen, it has been found that a continuous slot approximating inch in width is highly eflicient, combined with a flat upper surface 46 of width at least 10 times the width of the slot. In the example of the drawings, the slot width is 4 inch, and the upper surface width 4 inches, the slot being located centrally of the surface 46. It has also been found that the slot walls 50 are preferably cut perpendicular to the upper surface 46, so that the slot neither converges nor diverges.

End flanges 52 may be fixed as by welding to each end of the tube 32, and to one end flange is bolted or similarly engaged a disc cover 54. In the preferred embodiment, each end flange 52 is composed of two semicircular segments, welded respectively to the tube members 34 and 36. As shown in Figures 1 and 2, a drain pipe 56 may extend from the disc cover 54, and a connection 58 may extend therethrough, to provide communication from the interior of the tube to a manometer 60. To the opposite end flange 52 may be bolted an adapter 62, to which a conduit 64 may be suitably engaged as by threads.

Referring to Figures 1, 2 and 3, the extraction tube is conveniently mounted on pads 66 resting on the frame 10, each end of the tube extending through laterally spaced guide bars 68. A channel 70 extends across each corresponding pair of guide bars, and a threaded bolt 72, surmounted by ahandle 74, is threadably engaged to each channel whereby it may maintain a pad 76 in firm contact with the upper surface of the tube. As will be evident, this mounting serves to retain the extraction tube firmly in place. If desired, the channels 70 may be detachably bolted or otherwise fastened to the guide bars 62, whereby they may be readily removed for cleaning or replacement of the extraction tube.

In operation, the newly formed fabric 20 is led onto the screen 18, desirably at the position of roller 22. The screen 18 is driven at a suitable rate, preferably coordinated with the rate of formation of the fabric, by one of the engaged rollers, and the fabric is carried thereby under the immersion drum 14 and through the impregnating liquid. Since both the screen and the immersion drum are foraminous, the fabric is thoroughly impregnated in passing through the liquid. During this impregnation, as will be evident, the weak fabric is fully supported on both sides, and thereby protected against damage. On emerging from the liquid, the screen 18 and the wet fabric web thereon travel over roller 24 and then over the extraction tube.

The conduit 64 communicates with the inlet of a blower, not shown, whereby a constant vacuum is maintained in the extraction tube. One blower may serve two or more extraction tubes, and a damper in each conduit 64 may be provided to control the degree of vacuum in the associated extraction tube. In ordinary operations the vacuum maintained may range from about 1 to 6 inches of mercury.

The vacuum in the extraction tube causes air to be sucked through the slot 48, and through the overlying wet fabric and wire screen, thereby removing excess impregnant and leaving the fabric web open. One or more centrifugal separators may be interposed between the conduit 64 and the blower, to separate impregnating liquid from the air stream.

As previously noted, the length of the slot 48 slightly exceeds the width of the fabric web. A continuous slot of the dimensions and configuration specified has been found most effective to extract impregnant at high rate and uniformity. That is, the air movement and impregnant extraction are uniform along the length of the slot, and across the width of the fabric.

The wire screen being foraminous, it is possible for the slot 48 to suck air laterally therethrough, particularly from the downstream side which has already been extracted. Under ordinary circumstances, air may enter the suction tube in this manner in variable and uncontrolled manner, without passing through the fabric web, and the extraction of impregnant will be non-uniform. The side leakage effect, however, is minimized and reduced to a substantially constant value by use of a suificiently wide upper surface 46 on the extraction tube. As previously indicated, the upper surface 46 should be at least times the widthv of the slot 48, and it is of exceeding importance that the trailing portion of the upper surface, with respect to the slot and the direction of screen travel, be at least 5 times the width of the slot. The relative dimensional values may be affected slightly by the character of the screen, but are valid for most conventional types, such as screens of spiral and pin const-ruction. If the upper surface 46, then, is of suitable width, the major portion of the air entering the extraction tube passes through the fabric web, and no difliculty is encountered in maintaining steady the vacuum in the extraction tube, and achieving uniformity of impregnant extraction along the web length and across its width.-

The wire screen riding over the upper surface 46 in passage over the extraction tube tends to wear it severely. If the upper surface of the extraction tube is coated heavily with chromium, however, and polished, it has a greatly extended useful life, and the chromium coating enhances maintenance of an effective seal with the screen passing over the tube.

In operation of the vacuum extraction tube of the invention, there is only a very slight tendency of the web to condense into the wire screen in passing over the slot 48. The web does not imbed itself in the screen, but is only very slightly marked thereby and separates easily therefrom. In the extraction of excess impregnant through the supporting screen in the manner described, it has been found that the web is not materially condensed, and the desirable random fiber orientation thereof is not disturbed.

The quantity of impregnant remaining in the fabric after extraction may be controlled by varying the solids content of the impregnating bath, or more readily by varying the degree of vacuum maintained in the extraction tube. As will be evident, the extraction tube may be easily removed from the impregnation apparatus frame and disconnected, and then quickly disassembled for cleaning, a feature of considerable importance in equipment used with, for example, elastomeric latex impregnating compositions.

It will thus be seen that there has been provided by this invention a structure in which the vairous objects hereinbefore set forth, together with many practical advantages, are successfully achieved. As various possible embodiments may be made of the mechanical features of the above invention, all without departing from the scope thereof, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative, and not in a limiting sense.

We claim:

A vacuum extraction tube for use in impregnating nonwoven fabric comprising a flat upper surface on said tube, said surface having a single centrally disposed slot extending longitudinally thereof and communicating with the interior of said tube, said slot being approximately one fourth inch wide and defined by walls perpendicular to said upper surface, said upper surface having an overall width at least ten times the width of said slot, said tube being substantially square in cross section and comprising an integral upper and an integral lower section, said sections being substantially U-shaped in cross section and each having an outwardly extending right angle flange on each of its longitudinal edges, said flanges terminating a considerable distance from the ends of said tube, bolt means securing said flanges together in face to face relation, and an end flange fixed to each end of said tube and extending at right angles thereto, said end flanges each comprising two semi-circular segments each welded to one of said sections and defining a central opening communicating with the interior of said tube.

ReferencesCited in the file of this patent UNITED STATES PATENTS 1,161,030 Coppage Nov. 23, 1915 1,718,096 Wells June 18, 1929 1,790,852 Berry Feb. 3, 1931 1,859,869 Hadley May 24, 1932 1,926,306 Pettersen Sept. 13, 1933 1,939,578 Sullivan Dec. 12, 1933 2,003,397 Smith June 4, 1935 2,248,530 Granger et al July 8, 1941 2,648,876 Phillips et a1 Aug. 18, 1953 2,698,271 Clark Dec. 28, 1954 

